BLIND FASTENER EQUIPPED WITH A SELF-BREAKING HOLDING SYSTEM
A blind attachment that includes a body (36) with—at a first end—a visible surface (38), through which a bore (40) passes that accommodates a rod (42) of which a first end (44) projects relative to the visible surface (38) and of which the other end includes a head (46) that can deform a deformation zone (48) when the rod (42) moves translationally, with the visible surface including holding elements for coupling the body (36) to a tool that is used for driving the rod (42) in rotation, whereby the holding elements include at least one lug (52) that is connected at the visible surface (38) and that projects relative to the latter, characterized in that the at least one lug (52) is connected to the body (36) by a junction zone (54) that can break when the lug undergoes a force that exceeds a given threshold.
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This invention relates to a blind attachment equipped with a self-breaking holding system.
A blind attachment makes it possible to assemble parts while having access only to a single side of the assembly.
As illustrated in
To ensure the translational motion of the rod 14, one approach consists in providing a threaded rod 14 that is screwed into a threaded bore 12 of the body 10. The end 18 of the rod 14 comprises at least one flat surface for making it possible for a tool 22 to drive the rod 14 in rotation.
As illustrated in
According to one embodiment, a nut 28 can be interposed between the tool 22 and the surface 24 of the body.
According to an operating method, in a first step, the blind attachment is put into a bore 30 made in the parts 32 to be assembled, as illustrated in
Subsequently, it is advisable to plane down the threaded rod so that the latter is flush with the surface 24 of the body.
After the installation of the blind attachment and the application of paint, the slots 26 remain visible. Consequently, this type of attachment is not entirely satisfactory in terms of esthetics.
According to another point, when these slots 26 are arranged at the surface of the fuselage, they form rough spots that create disturbances on the aerodynamic plane.
The purpose of this invention is to eliminate these drawbacks.
For this purpose, the object of this invention relates to a blind attachment that comprises a body with a visible surface at a first end, through which a bore that accommodates a rod passes and whose first end projects relative to the visible surface and whose other end comprises a head that can deform a deformation zone when the rod moves translationally, with the visible surface comprising holding means for coupling the body to a tool that is used to drive the rod in rotation, whereby said holding means comprise at least one lug that is connected to the visible surface and that projects relative to the latter, characterized in that said at least one lug is connected to the body by a junction zone that can break when the lug is subject to a force that exceeds a given threshold. After the installation of the attachment, this approach makes it possible to obtain a visible surface without recessed rough spots. Advantageously, at the junction zone, each lug comprises at least one notch that makes it possible to obtain a small cross-section and to track the rupture of the lug. According to one embodiment, for each lug, the notch is made at the base of the lug.
In addition, the invention proposes a tool for installing a blind attachment according to the invention, characterized in that it comprises a front surface, able to rest against the visible surface of the blind attachment, with at least one slot for housing a lug.
Advantageously, the tool has two directions of rotation, a first direction for causing the deformation of the blind attachment and the rupture of the rod, and a direction that is opposite to the first for causing the rupture of the lug(s).
According to one embodiment, at each slot, the tool comprises a wedge shape that can penetrate a notch of a corresponding lug.
As a variant, each slot comprises a surface that rests at a distance from the bottom of a notch that is made at the corresponding lug so as to create a moment that facilitates the rupture of the lug(s).
Other characteristics and advantages will emerge from the following description of the invention, a description that is provided only by way of example, relative to the accompanying drawings in which:
As illustrated in
The blind attachment comprises a deformation zone 48 that can deform because of compressive forces exerted by the head 46 when the rod 42 moves translationally upward.
According to one variant, the deformation zone 48 is a sleeve 49 that is interposed between the head 46 and the body 36.
According to another variant, the deformation zone 48 is provided at the end of the body 36 that is oriented toward the head.
According to one variant, to ensure the relative translational movement between the rod 42 and the body 36, the rod 42 is threaded and screwed into the bore 40 that is tapped. In particular, a tool can impress a movement of rotation on the threaded rod 42. To do this, the end 44 of the threaded rod comprises a flat surface for making it possible to couple the threaded rod 42 to a rotary tool.
According to another variant, a tool can pull on the end 44 of the threaded rod so that the latter moves translationally.
The rod 42 comprises a rupture initiator that makes it possible to cut it into sections in a plane that is flush with the visible surface 38 when the deformation zone is deformed in a suitable manner. According to one embodiment, the rod 42 comprises a notch at the rupture plane 50 that is visible in
According to the different variants, the visible surface 38 comprises holding means for coupling the body 36 to a tool, provided either for immobilizing the blind attachment in rotation, in particular when the threaded rod 42 is put into rotation for deforming the deformation zone 48, or for subjecting a torque to the blind attachment, in particular after the rod 42 is broken to verify the good tightening of the attachment.
According to the invention, the holding means comprise at least one lug 52 that is connected at the visible surface 38 and that projects relative to the latter. The lug 52 is connected to the body 36 by a junction zone 54 that can break when the lug undergoes a force that exceeds a given threshold, called a lug rupture threshold, which is less than the mechanical strength of the blind attachment so as not to damage it.
In addition, as illustrated in
Advantageously, the blind attachment comprises several lugs 52 for distributing the forces and for ensuring that the body is held during the deformation of the zone 48 and the cross-section of the rod 42.
In addition, the tool 56 comprises a number of slots 64 that is at least equal to that of the lugs 52, with the slots 64 being arranged at the frontal surface 60 in a manner that is suitable for housing the lugs 52.
For each lug, the junction 54 between the lug 52 and the body 36 is sized in such a way as to break when the force exerted by the tool reaches the lug rupture threshold.
Thus, as illustrated in
Advantageously, the lugs 52 are cut into sections at the plane of the visible surface 38. Thus, after its installation, the blind attachment does not need to be planed down and has a flat surface as illustrated in
For this purpose, each lug 52 comprises—at the junction zone 54—at least one notch 66 that makes it possible to obtain a small cross-section and to track the rupture of the lug at the plane of the visible surface 38.
For each lug, the notch 66 is made at the base of the lug, from the side where the force of the tool is applied to cut the lug into sections.
The notch 66 can have different shapes as illustrated in
According to one embodiment, for at least one lug, the notch 66 is delimited by two parallel surfaces 68, 68′, one of the two surfaces 68 being arranged in the plane of the visible surface 38, as illustrated in
According to an embodiment that is illustrated in
According to a first operating mode, the relative rotational movement between the visible surface 38 of the body and the frontal surface 60 of the tool 56 that is necessary for breaking the lugs 52 has the same direction as the one that is necessary for causing the deformation of the blind attachment and the rupture of the threaded rod 42.
In this case, the lug rupture threshold is greater than the force that is necessary for cutting the rod 42 into sections, which is itself greater than the one that is necessary for deforming the deformation zone 48 completely.
According to another operating mode, the tool has two directions of rotation. Thus, the relative rotational movement between the visible surface 38 of the body and the frontal surface 60 of the tool 56 that is necessary for breaking the lugs 52 has a direction that is opposite to the one that is necessary for causing the deformation of the blind attachment and the rupture of the rod 42.
Each lug 52 has two surfaces 72, 72′ that are arranged in two essentially radial planes, one of them 72′ having a notch 66 at its base. In parallel, each slot 64 of the tool 56 comprises two surfaces 74, 74′ that are arranged in two essentially radial planes, with a first surface 74 being able to rest against the surface 72 of the lug for immobilizing the body 36 in rotation during its rotating of the rod 42, as illustrated in
This reversal of direction makes it possible to create an operation that is clearer for the operator, who can distinguish between the two installation phases, namely the deformation phase of the deformation zone to the rupture of the rod 42 and then the rupture phase of the lugs. This reversal of direction also makes it possible to verify the good mechanical hold of the deformation zone and that the blind attachment is prestressed well.
Advantageously, in the first direction of rotation, the tool is in contact with the base of each lug, as illustrated in
According to another variant that is illustrated in
Claims
1. Blind attachment comprising a body (36) with—at a first end—a visible surface (38), through which a bore (40) passes that accommodates a rod (42) of which a first end (44) projects relative to the visible surface (38) and of which the other end comprises a head (46) that can deform a deformation zone (48) when the rod (42) moves translationally, with the visible surface comprising holding means for coupling the body (36) to a tool that is used for driving the rod (42) in rotation, whereby said holding means comprise at least one lug (52) that is connected at the visible surface (38) and that projects relative to the latter, characterized in that said at least one lug (52) is connected to the body (36) by a junction zone (54) that can break when the lug (52) undergoes a force that exceeds a given threshold.
2. Blind attachment according to claim 1, wherein each lug (52) comprises—at the junction zone (54)—at least one notch (66) that makes it possible to obtain a small cross-section and to track the rupture of the lug (52).
3. Blind attachment according to claim 2, wherein for each lug (52), the notch (66) is made at the base of the lug.
4. Blind attachment according to claim 3, wherein for at least one lug, the notch (66) has a triangular cross-section with a surface (70) that is arranged in the plane of the visible surface (38) and another surface (70′) that makes an angle that is less than or equal to 60°.
5. Blind attachment according to claim 3, wherein for at least one lug, the notch (66) is delimited by two parallel surfaces (68, 68′), with one of the two surfaces (68) being arranged in the plane of the visible surface (38).
6. Blind attachment according to claim 2, wherein for each lug, a notch (66) is made on one surface of the lug at which a tool for cutting it into sections can rest.
7. Tool for installing a blind attachment according to claim 1, wherein it comprises means for coupling to the rod (42) and a frontal surface (60), able to rest against the visible surface (38) of the blind attachment, with at least one slot (64) for housing a lug (52).
8. Tool according to claim 7, wherein it has two directions of rotation, a first direction for causing the deformation of the blind attachment and the rupture of the rod (42) and a reverse direction for causing the rupture of the lug(s) (52).
9. Tool according to claim 7, wherein it comprises—at each slot (64)—a wedge shape (78) that can penetrate a notch (66) of a corresponding lug (52).
10. Tool according to claim 7, wherein each slot comprises a surface that rests at a distance from the bottom of a notch (66) that is made at the level of the corresponding lug in such a way as to create a moment that facilitates the rupture of the lug(s).
11. Blind attachment according to claim 3, wherein for each lug, a notch (66) is made on one surface of the lug at which a tool for cutting it into sections can rest.
12. Blind attachment according to claim 4, wherein for each lug, a notch (66) is made on one surface of the lug at which a tool for cutting it into sections can rest.
13. Blind attachment according to claim 5, wherein for each lug, a notch (66) is made on one surface of the lug at which a tool for cutting it into sections can rest.
14. Tool according to claim 8, wherein it comprises—at each slot (64)—a wedge shape (78) that can penetrate a notch (66) of a corresponding lug (52).
15. Tool according to claim 8, wherein each slot comprises a surface that rests at a distance from the bottom of a notch (66) that is made at the level of the corresponding lug in such a way as to create a moment that facilitates the rupture of the lug(s).
Type: Application
Filed: Jan 13, 2012
Publication Date: Jul 19, 2012
Patent Grant number: 9163652
Applicant: AIRBUS OPERATIONS (SAS) (TOULOUSE)
Inventors: Jean-Baptiste TUERY (TOULOUSE), Clément CHIROL (TREBONS SUR LA GRASSE)
Application Number: 13/349,720
International Classification: B23P 11/00 (20060101); F16B 23/00 (20060101);